One way of knowing how deep a crankbait is running is to troll parallel to the bank and gradually move shallower keeping an eye on your depthfinder until your lure starts bumping the bottom.
You always hear the pro's say I am trolling so many feet down. How do they know how deep they are when the lure is behind them up to 100 feet or more. Is there a way you can know that a specific lure and weight combination will give a specific depth. With all the variables like: Line weight, lure type, bill size and shape, line distance, boat speed, and others I suppose, I don't see how they can say so accurately. Maybe they say that because they are on TV, LOL.
One way of knowing how deep a crankbait is running is to troll parallel to the bank and gradually move shallower keeping an eye on your depthfinder until your lure starts bumping the bottom.
maybe they use the trolling bible. mine is very handy.
http://www.precisionangling.com/
Cody.
another theory is the weight, some bass fishermen i know will throw a bait ,count to a certain number (depending on the depth they want) then reel in. I believe it is all in the experience with different lures and how they work. and then there are the trollers. They definately after losing a few high dollar baits know exactly what they will do and how deep and motor speed and all that jazz.
HOLD YO HEAD UP MULEY